diff --git a/scripts/install-essentials b/scripts/install-essentials
index e4bb75e..d9147f7 100755
--- a/scripts/install-essentials
+++ b/scripts/install-essentials
@@ -14,3 +14,5 @@ apt-get install -y \
 	$PACKAGES
 
 rm -rf /var/lib/apt/lists/*
+
+gem install knapsack